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I'm a well-known mainframe performance guy, with almost 30 years of experience helping customers manage systems. I also dabble in lots of other technology. I've sought to widen the Performance role, incorporating aspects of infrastructural architecture.
I'm a world-famous podcaster and screencaster (albeit VERY thinly spread). :-)

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There's a pattern I've seen over a number of test Parallel Sysplex environments over the past few years, a couple of them in situations this year: It's not much use drawing performance inferences from test environments if they're not set up properly for performance tests. Sounds obvious, doesn't it? There are two problem areas I want to draw your attention to: Shared Coupling Facility Images If... [More]

In recent releases RMF have put the machine serial number into both SMF Type 74 Subtype 4 (Coupling Facility Activity) and SMF Type 70 Subtype 1 (CPU Activity). Actually we get two fields in each case: Plant Number and Sequence Number, which you can put together as eg "51-12345". Soon we'll get another piece of the jigsaw: Partition Number in 74-4. This is a small change but a nice useful one...... [More]

In the same meeting with RMF Development as ERBSCAN / ERBSHOW was discussed we talked about Parallel Sysplex instrumentation. (Both XCF and Coupling Facility aspects.) One thing I hadn't noticed is the appearance of Subchannel Busy Percentage as a number in the following three places: In Monitor III In the Spreadsheet Reporter As Overview Condition ("SUBCHBP") I think you can do useful work with... [More]

I'm not sure if anyone's done this before. Certainly I've not seen any results... We're beginning to write up some tests the "A Team" (Alain and Pierre) ran before their return to France. Which provides me with some test data. Fortunately I had a stab at mapping the new fields this data contains. One in particular is Stucture CPU (R744SETM)... So, I got to plotting CPU per request against request... [More]

It's fair to say I've written very little in terms of book words these past two days. That's because I've been "doing research" on how the cache structure counters really work. "Doing research" is a euphemism for "finding out how the heck the darned thing works". Which is in itself a positive thing to do - but it does rather get in the way of writing stuff. :-( There is a section in the SMF 74... [More]

I had to eat a little bit of humble pie today - because I made an elementary mistake. I'm going to share it with you - to save you making it, too. :-) And I'm very sure I'm not going to make it in a customer situation. (Residencies are great for making mistakes in a safe environment.) :-) In CFLEVEL 15 and z/OS Release 9 RMF you get a new field at the structure level: R744SETM. This is the CPU... [More]

Sometimes reading the SMF manual buys you less than you thought. I had completely ignored a nice little field - and the code I inherited to analyse SMF 74 Subtype 4 Coupling Facility data ignored it as well. R744SLEC in the Request Data Section for a structure is described by the text "Lock structure only: lock table entry characteristic". Can you guess what it is? :-) If I told you it was a one... [More]

The other three residents are busy doing extensive setup work - and we hope to have some nice measurements later on. (I'm not sure how much later on there actually is, mind.) :-) So I have no RMF or DB2 SMF to play with yet. :-( Meanwhile I'm beginning to come up to speed again after the glorious experience of recovering from moving five time zones to the west. :-) So I actually got to writing... [More]

So, I'm about to start writing. At last! As a team we had a discussion yesterday about how to deal with performance numbers. One of the roles I'm playing on the team is "the guy who writes about performance numbers". So we came to the following conclusions: We really can't talk about products made by other people - such as SAS/MXG or TMON for DB2. That's right out - because of our basic provenance... [More]

I wonder how many of you recognise the terms "READ_COCLASS", "WARM", "RFCOM","WRITE_DATALIST" and "CASTOUT_DATALIST". Granted that in that list are two pairs of terms that I believe to be synonymous, but all five are relatively recent enhancements to Parallel Sysplex infrastructure that have a positive impact on DB2 Data Sharing performance (or at least the management of Performance). As I... [More]

I presented to the Large Systems GSE meeting in Dudley on Wednesday on "DB2 Data Sharing Performance For Beginners" and an interesting question came up... "At what distance does performance begin to suffer when moving machines in a parallel sysplex apart?" As it happens I am dealing with exactly that question in a customer right now. It seems it's a popular thing to attempt. (I know: One user... [More]